This proposal addresses the significant public health threat posed by the liver flukes Clonorchis sinensis and Opisthorchis viverrini in at-risk human populations including personnel stationed in Southeast Asia for military or government service in previous decades. Infection with the two liver flukes is associated with a greater risk for cholangiocarcinoma, a highly lethal cancer of the bile ducts. Clonorchiasis and Opisthorchiasis affect over 35 million people worldwide, principally in endemic regions of East and Southeast Asia. As liver fluke infection can persist up to several decades, military service personnel, immigrants and travelers returning from these areas may continue to experience active infection. Diagnostic tests that can detect liver fluke infections are not readily available in the U.S. In this project, screening and point-of-care serological tests will be developed. Phase I will focus on identification of suitable antigens with high sensitivity and high specificity for the two parasites, development of prototype ELISA and lateral flow assays and demonstration of feasibility through assessment of prototype assay performance on sera from liver fluke patients and controls. The proposed ELISA and lateral flow assays will be the first highly accurate tests for Clonorchiasis and Opisthorchiasis to be made available commercially in the U.S.